The three-dimensional imaging with C-arm x-ray devices was hitherto only implemented statically, i.e. without temporal information.
To this end, the C-arm rotates by approximately 200° (180°+fan angle) about the patient and in this way records between 50 and 1000 images of the patient. A three-dimensional image can be obtained from these recordings from different projection directions with the aid of a suitable reconstruction method, like for instance the filtered back projection, which is described in “Practical Cone-beam Algorithm” by Feldkamp et al., J. Opt. Soc. Amer. A, Vol. 1, No. 6, June 1984, pages 612 to 619, or the algorithm described by Klaus Mueller et al. in “A Fast and Accurate Projection Algorithm for 3D Cone-Beam Reconstruction with the Algebraic Reconstruction Technique (ART)”.
Two rotational runs are generally implemented in order to represent vascular trees. A contrast agent is injected into the vessel to be displayed in the second rotational run. A three-dimensional image in which only the contrast agent-filled vessels are displayed is obtained by subtracting both runs and a subsequent reconstruction.
The functional imaging, like for instance perfusion imaging, is generally implemented using CT and MR. These imaging modalities are however generally not available in an interventional setting.
DE 10 2004 057 308 A1 relates to an angiographic x-ray diagnostics device for rotation angiography comprising an x-ray emitter which can be moved on a circular path, an opposing image detector unit which can be moved on a circular path, a digital imaging system for recording a plurality of projection images, a device for reconstructing a 3D volume image and a device for correcting physical effects and/or inadequacies in the recording system such as truncation correction, scattered radiation correction, irradiation correction, ring artifact correction, correction of the beam hardening and/or of the low frequency drop for the soft tissue representation of projection images and the 3D volume images reconstructed therefrom.
In the former patent application DE 10 2006 035 067.7, a method for the temporal and three-dimensional representation of a periodically changeable structure is described, in which several rotational exposures are created. The necessary rotational runs are started at an identical event of the period process offset by a specific angle. New image series are combined from the rotational exposures, whereby three-dimensional representations are reconstructed to form different phase regions of the periods.